Backups: show free disk space on upload+restore page

Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/modules/backups/templates/backups_upload.html

@@ -32,7 +32,10 @@
       You can choose the apps you wish to import after uploading a backup file.
     {% endblocktrans %}
   </p>
-  <br />
+  <div class="alert alert-info" role="alert">
+    {% trans "Free disk space" %}: {{ free_space }}<br />
+    {% trans "Make sure the uploaded file is smaller than that." %}
+  </div>
 
   <form class="form" enctype="multipart/form-data" method="post">
     {% csrf_token %}

plinth/modules/backups/views.py

@@ -21,6 +21,7 @@ Views for the backups app.
 from datetime import datetime
 import gzip
 from io import BytesIO
+import logging
 import mimetypes
 import os
 import tempfile
@@ -36,12 +37,15 @@ from django.utils.translation import ugettext as _
 from django.utils.translation import ugettext_lazy
 from django.views.generic import View, FormView, TemplateView
 
-from plinth.modules import backups
 from plinth import actions
+from plinth.errors import PlinthError
+from plinth.modules import backups, storage
 
 from . import api, forms, SESSION_PATH_VARIABLE
 from .decorators import delete_tmp_backup_file
 
+logger = logging.getLogger(__name__)
+
 subsubmenu = [{
     'url': reverse_lazy('backups:index'),
     'text': ugettext_lazy('Backups')
@@ -142,6 +146,13 @@ class UploadArchiveView(SuccessMessageMixin, FormView):
         context = super().get_context_data(**kwargs)
         context['title'] = _('Upload and restore a backup file')
         context['subsubmenu'] = subsubmenu
+        try:
+            disk_info = storage.get_disk_info('/', self.request)
+        except (PlinthError, PermissionError):
+            logger.error('Error getting information about root partition.')
+        else:
+            context['free_space'] = storage.format_bytes(
+                    disk_info["free_bytes"])
         return context
 
     def form_valid(self, form):

plinth/modules/storage/__init__.py

@@ -25,8 +25,9 @@ from django.utils.translation import ugettext_lazy as _
 
 from plinth import service as service_module
 from plinth import action_utils, actions, cfg
+from plinth.errors import PlinthError
 from plinth.menu import main_menu
-from plinth.utils import format_lazy
+from plinth.utils import format_lazy, is_user_admin
 
 from .manifest import backup
 
@@ -77,6 +78,24 @@ def get_disks():
     return combined_list
 
 
+def get_disk_info(mountpoint, request):
+    """Get information about the free space of a drive"""
+    if not is_user_admin(request, cached=True):
+        raise PermissionError
+    disks = get_disks()
+    list_root = [disk for disk in disks if disk['mountpoint'] == mountpoint]
+    if not list_root:
+        raise PlinthError
+    percent_used = list_root[0]['percent_used']
+    free_bytes = list_root[0]['free']
+    free_gib = free_bytes / (1024**3)
+    return {
+        "percent_used": percent_used,
+        "free_bytes": free_bytes,
+        "free_gib": free_gib
+    }
+
+
 def _get_disks_from_df():
     """Return the list of disks and free space available using 'df'."""
     command = [

plinth/modules/storage/views.py

@@ -30,10 +30,11 @@ from django.utils.translation import ugettext as _
 from django.views.decorators.http import require_POST
 
 from plinth import actions
+from plinth.errors import PlinthError
 from plinth.modules import storage
-from plinth.utils import format_lazy, is_user_admin
+from plinth.utils import format_lazy
 
-from . import udisks2
+from . import udisks2, get_disk_info
 
 logger = logging.getLogger(__name__)
 
@@ -91,29 +92,22 @@ def expand_partition(request, device):
 
 def warn_about_low_disk_space(request):
     """Warn about insufficient space on root partition."""
-    if not is_user_admin(request, cached=True):
-        return
-
-    disks = storage.get_disks()
-    list_root = [disk for disk in disks if disk['mountpoint'] == '/']
-    if not list_root:
+    try:
+        root_info = get_disk_info('/', request)
+    except (PlinthError, PermissionError):
         logger.error('Error getting information about root partition.')
         return
 
-    percent_used = list_root[0]['percent_used']
-    free_bytes = list_root[0]['free']
-    free_gib = free_bytes / (1024**3)
-
     message = format_lazy(
         # Translators: xgettext:no-python-format
         _('Warning: Low space on system partition ({percent_used}% used, '
           '{free_space} free).'),
-        percent_used=percent_used,
-        free_space=storage.format_bytes(free_bytes))
+        percent_used=root_info["percent_used"],
+        free_space=storage.format_bytes(root_info["free_bytes"]))
 
-    if percent_used > 90 or free_gib < 1:
+    if root_info["percent_used"] > 90 or root_info["free_gib"] < 1:
         messages.error(request, message)
-    elif percent_used > 75 or free_gib < 2:
+    elif root_info["percent_used"] > 75 or root_info["free_gib"] < 2:
         messages.warning(request, message)